GM Service Manual Online
For 1990-2009 cars only
To wash your windshield, press and hold the windshield washer paddle. The washers and wipers will operate. When you release the paddle, the washers will stop, and the wipers will continue to operate for two cycles, unless your wipers were already on. In that case, the wipers will resume the wiper speed you had selected earlier.

Caution: In freezing weather, do not use your washer until the windshield is warmed. Otherwise the washer fluid can form ice on the windshield, blocking your vision.